package com.learning.demos;

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/**
 * @author adolphw
 *
 * 题目：一个初始值为0的变量，两个线程对其交替操作，一个加1，一个减1，来5轮
 *
 * 1 线程 操纵 资源类
 * 2 判断 干活 通知
 * 3 防止虚假唤醒
 *
 */
public class ProdConsumerTraditionDemo {
    public static void main(String[] args) {

        ShareData shareData = new ShareData();

        new Thread(() -> {
            for (int i = 0; i < 5; i++) {
                try {
                    shareData.increment();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "aaaa").start();

        new Thread(() -> {
            for (int i = 0; i < 5; i++) {
                try {
                    shareData.decrement();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "bbbb").start();

        new Thread(() -> {
            for (int i = 0; i < 5; i++) {
                try {
                    shareData.increment();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "cccc").start();

        new Thread(() -> {
            for (int i = 0; i < 5; i++) {
                try {
                    shareData.decrement();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "dddd").start();

    }
}

class ShareData{
    // 资源类
    private int number = 0;

    private Lock lock = new ReentrantLock();

    private Condition condition = lock.newCondition();

    public void increment() throws InterruptedException {
        lock.lock();

        try {
            // 判断
            while (number != 0) {
                // 等待 不能生产
                condition.await();
            }

            // 干活
            number++;
            System.out.println(Thread.currentThread().getName() + "\t " + number);

            // 通知
            condition.signalAll();

        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            lock.unlock();
        }

    }

    public void decrement() throws InterruptedException {
        lock.lock();

        try {
            // 判断
            while (number == 0) {
                // 等待 不能生产
                condition.await();
            }

            // 干活
            number--;
            System.out.println(Thread.currentThread().getName() + "\t " + number);

            // 通知
            condition.signalAll();

        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            lock.unlock();
        }

    }
}
